Seasonality in the Trans-Atlantic Slave Trade

Stephen D. Behrendt (Victoria University of Wellington), 2008


In many markets in the Atlantic world monthly cycles of slave exports and imports, documented in the Voyages Database, link to dry season crop harvests. African and European dealers on the African coast purchased provisions and slaves. Some markets, such as those along the Senegal and Gambia Rivers, had distinct provisioning-slaving seasons. Ecological conditions set agricultural calendars and the dates when workers gathered and stored foodstuffs. African middlemen pegged their slave-trading seasons to in-crop months, and some agricultural workers, sold into the overseas slave trade, may have been forced to consume the foods they produced. By moving captives between harvests on the Atlantic littoral, slaving ship captains created regular pathways, such as those between yam-growing Bight of Biafra and the sugar islands of the Caribbean, or those between millet-rice Upper Guinea region and North American rice and tobacco lands. In examining slave trading routes, historians need to consider agricultural calendars on both sides of the Atlantic.

Though there were monthly cycles of slave exports and imports, year-round shipments took place in all markets during the 350-year history of the trans-Atlantic slave trade. In the most seasonal African slaving region—Senegambia—about fifteen percent of all enslaved Africans departed the coast in the out-of-crop, rainy, September-November quarter. Even in the most seasonal market in the Atlantic slaving world—the northern plantations of Virginia and Maryland (36-39° N)—small numbers of forced migrants arrived in the winter, when no crops were grown. In the large Bight of Biafra – Jamaica migration stream, forty percent of enslaved Africans arrived on the island during the June-November out-of-crop season. And many would have sailed from Bonny, Old Calabar or New Calabar from April to July when yam stocks were low or depleted. Variability in the Middle Passage voyage time, due to contrary winds, caused some captains to arrive out of season; one assumes that there also was variability in the time taken to march captives towards the African coast.

It is important to examine these unseasonal slave trades. In Africa, they remind us that the slave trade was a predatory activity. Warfare between African states often took place after the principal grain harvest and during the dry season, but conflicts could erupt at any time, and during every day of the year raiders could attack communities or kidnap people. Seasonal rainfall and crop-growing constraints did not completely limit the plunder of people. Captains who traded towards the end of “in-crop” seasons in Africa, such as Robert Doegood, risked purchasing greater numbers of malnourished men, women and children. Doegood traded at New Calabar when yam supplies were low; his logbook reveals that eighty Africans died on the Middle Passage (of 348 people) and four more in harbor at Barbados. Historians should examine more closely the links between provisioning-slaving seasons and mortality. In the Americas, investors were willing to purchase enslaved labor from any African region during any day of the year—the labor of enslaved Africans maintained the Colonial System. Trading during out of crop seasons, on both sides of the Atlantic, increased the chances that irregular, non-systematic migration patterns occurred—a true diaspora or “scattering” of African peoples in the Americas.

Trans-Atlantic pathways and harvest cycles
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